Fluoroscopic templating technique for precision arthroscopic rim trimming

Arthroscopic acetabular labrum suture

It is essential to be aware of the anatomy and biomechanics of the acetabular labrum in order to understand why it should be conserved. Vascularization comes from the capsule and also from the bone. The joint side contains numerous nerve endings, which explains why labral lesions are painful. It is involved in joint stabilization by maintaining a negative pressure inside the joint able to resist distraction. It acts as a seal. There are two main suture techniques: trans- and peri-labral. Translabral suture is better suited to a wide and solid labrum free of degenerative lesions. Both techniques should be known, and may be associated. Results are comparable. It is essential to manage the underlying pathology responsible for the labral lesion. Joint degeneration is associated with poor prognosis. It needs to be recognized and discussed with the patient, to avoid unrealistic expectations.

Improved Functional Outcome Scores Associated with Greater Reduction in Cam Height Using the Femoroacetabular Impingement Resection Arc During Hip Arthroscopy

PURPOSE

We sought to evaluate the association between postoperative cam lesion measured by the femoroacetabular impingement resection (FAIR) arc and show 2-year patient outcomes following hip arthroscopy.

METHODS

A retrospective review of prospectively gathered data from 2013-2017 was performed. All patients who underwent hip arthroscopy for femoroacetabular impingement resection (FAI) with ≥2-year follow-up were included. Cam FAIR arc measurements were made preoperatively and postoperatively on a 45° Dunn view radiograph. The clinical effect of postoperative cam maximal radial distance (MRD) was assessed using the modified Harris Hip Score (mHHS) and Non-Arthritic Hip Score (NAHS). Patients were divided into subgroups based on relationship to the mean and standard deviations for cam MRD. One half standard deviation above the mean was found to be 3.15 mm.

RESULTS

Sixty-one hips in 59 consecutive patients (age 38.1 ± 13.1; body mass index [BMI]: 25.5 ± 4.3; 36 females) were included. Mean preoperative and postoperative cam maximal radial distances (MRD) were 4.5 ± 1.7 mm and 2.3 ± 1.7 mm (P < .001), respectively. The interclass correlation coefficient was excellent (>.9) for all measurements. There were no differences in age, sex, BMI or preoperative mHHS/NAHS between <3.15 mm and >3.15 mm cam MRD groups (P > .05). Using linear regression, cam MRD was found to be significantly associated with 2-year outcomes for both mHHS (R² = .21, P < .001) and NAHS (R² = .004). Subgroup analysis demonstrated that patients in the cam MRD < 3.15 mm group had significantly higher mHHS (89.7 vs 70.0, P < .001) and NAHS scores (90.5 vs 72.9, P < .001) than those in the >3.15 mm group. Additionally, more patients in the <3.15 mm group reached the minimal clinically important difference (95.2% vs 78.9%, P = .048) and were above patient acceptable symptomatic state (95.2% vs 52.6%, P < .001) compared to the >3.15 mm group.

CONCLUSION

Patients with a lower postoperative cam MRD relative to the FAIR arc demonstrated significantly improved outcomes as compared to those with higher postoperative MRD at two-year follow-up.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Rear drop: a new radiographic landmark for estimation of pelvic tilt on pelvis AP radiographs

Estimation of pelvic tilt on anteroposterior (AP) pelvis radiograph is often done by indirect methods based on the midline pelvic landmarks. The purpose of this cadaveric study is to describe a new radiographic landmark and reference measurements to estimate the coronal tilt of the pelvis, independent of the midline references. The new radiologic reference is called 'rear drop', and its anatomic location is described with the cadaveric pelvis AP radiographs in various pelvic inclination. The parameters derived from the new reference were used to assess the pelvic tilt, and the results were compared with the previously established method using 'sacrococcygeal joint to symphysis distance' (SCSD). The shape of the new figure is used to determine the position of the pelvis, and its relationship with the previously described acetabular retroversion indicators was statistically analyzed. The new reference figure corresponds to the posteroinferior edge of the horseshoe shape of the acetabular margin. The newly derived reference parameters, rear to tear distance and rear to tear angle, changes with pelvic tilt and are strongly correlated with SCSD. The shape of the rear drop changes with the changing pelvic tilt and correlates statistically with the previously described acetabular retroversion indicators. Rear drop and its derivative measurements can be used as a reliable and reproducible indicator to estimate the coronal pelvic tilt, free of midline reference points. This new reference will be a base for future clinical studies on pelvic tilt, rotation and their application in intraoperative hip fluoroscopy.

The Femoroacetabular Impingement Resection (FAIR) Arc: An Intraoperative Aid for Assessing Bony Resection During Hip Arthroscopy

Symptomatic femoroacetabular impingement is one of the most common hip pathologies in young athletes. Intraoperative fluoroscopy is commonly used during hip arthroscopy to aid with portal placement and resection of the cam and pincer lesions. However, there are currently no universally agreed-on tools to allow for the assessment of adequacy of femoral and acetabular osteoplasty. Despite the general lack of consensus among hip arthroscopists, the senior author recommends using the femoroacetabular impingement resection arc to guide the adequacy of cam and pincer resection in hip arthroscopy. Using intraoperative fluoroscopy, one should aim to create a continuous "Shenton's line"-type arc along the inferior aspect of the anterior-inferior iliac spine and superolateral femoral neck base by resecting any bone that causes a break in the continuity of this arc.

Teamwork in hip preservation: the ISHA 2019 Annual Scientific Meeting

Hip preservation surgery is now an established part of orthopedic surgery and sports medicine. This report describes the key findings of the 11th Annual Scientific Meeting of International Society for Hip Arthroscopy-the International Hip Preservation Society-in Madrid, Spain from 16 to 19 October 2019. Lectures, seminars and debates explored the most up-to-date and expert views on a wide variety of subjects, including: diagnostic problems in groin pain, buttock pain and low back pain; surgical techniques in acetabular dysplasia, hip instability, femoroacetabular impingement syndrome, labral repair and reconstruction, cartilage defects, adolescent hips and gluteus medius and hamstring tears; and new ideas about femoral torsion, hip-spine syndrome, hip capsule surgery, impact of particular sports on hip injuries, registries, robotics and training for hip preservation specialists. Surgeons, sports physicians, radiologists and physiotherapists looking after young people with hip problems have an increasingly sophisticated armoury of ideas and techniques with which to help their patients. The concept of hip preservation has developed incredibly fast over the last decade; now it is clear that the best results can only be achieved by a multidisciplinary team working together. The 2020s will be the decade of 'Teamwork in Hip Preservation'.

Use of a 3D virtual dynamic hip model to quantify the amount of osteoplasty required in femoroacetabular impingement patients

OBJECTIVE

Compare required osteoplasty predicted by a 3D virtual dynamic hip model in femoroacetabular impingement patients to actual osteoplasty performed.

MATERIALS AND METHODS

Retrospective study on 20 consecutive FAI patients with a preoperative CT who underwent arthroscopy from October 2016 to September 2017. A 3D virtual dynamic hip model was created from the CT. The model displayed virtual osteoplasty depth required to restore physiologic range of motion on an osteoplasty map. Depths of virtual osteoplasty and actual osteoplasty at surgery were compared and correlated with alpha angle, lateral center edge angle, femoral version, and acetabular version.

RESULTS

Actual femoroplasty depth correlated with alpha angle (r = 0.85, p ≤ 0.001) and actual acetabuloplasty depth correlated with lateral center edge angle (r = 0.83, p < 0.001). Virtual osteoplasty depth did not correlate with alpha angle (p = 0.25), lateral center edge angle (p = 0.50), femoral version (p = 0.09), or acetabular version (p = 0.09). The 3D model predicted a mean virtual osteoplasty of 6.2 ± 0.3 mm compared to mean actual osteoplasty of 5.9 ± 1.1 mm. There was no significant difference between the two means (p = 0.26), though there was a significant difference in variance (p = 0.001). There was poor test reliability between virtual osteoplasty compared with actual osteoplasty (ICC = 0.30).

CONCLUSION

3D model predicted virtual osteoplasty depths varied with actual osteoplasty and was independent of 2D measurements.

Hip Arthroscopy for Diffuse Idiopathic Skeletal Hyperostosis Using a Capsulotomy-First Approach

Diffuse idiopathic skeletal hyperostosis (DISH) is a systematic disease of unknown etiology characterized by ossification at the site of spine and major joints entheses, including the hip. Ossified connective tissue may cause pain and joint stiffness, which may require surgical intervention. The purpose of this study was to investigate the clinical, radiographic, and arthroscopic presentation and surgical outcomes of patients with DISH involving the hips. Fourteen hips in 9 patients (mean±SD age, 63±14 years; range, 35-76 years) with overcoverage of the femoral head by DISH were retrospectively reviewed. For all joints, a transverse, capsulotomy-first approach was performed due to an inability to access the central compartment by traction of the lower extremity. After arthroscopic resection of the ossified lesion, labral reconstruction was performed with an iliotibial band autograft. For clinical evaluation, patient-reported outcome scores (modified Harris Hip Score [mHHS], Nonarthritic Hip Score [NAHS], International Hip Outcome Tool-12 [iHot-12], visual analog scale [VAS] pain score, and VAS satisfaction score) were obtained. Arthroscopically, circumferential labral damage with no or mild articular cartilage damage was observed. Mean NAHS, iHot-12 score, and VAS satisfaction score improved significantly (47 to 56, 43 to 71, and 21 to 72, respectively; P<.05). Mean mHHS and VAS pain score did not reach significance but did improve (65 to 92 and 45 to 78, respectively). Using a transverse, capsulotomy-first approach for arthroscopic hip surgery for patients with DISH yields successful outcomes in patient-reported outcome measures and satisfaction, despite minor gains in hip range of motion. [Orthopedics. 2020;43(5):e369-e377.].

Mirror Image Modeling of Acetabular Rim Thickness Differences in Patients With Unilateral Femoroacetabular Impingement Syndrome

Purpose

To use mirror imaging to identify the location and magnitude of difference in acetabular rim morphology between the symptomatic and unaffected acetabula in patients with symptomatic unilateral pincer-type or mixed femoroacetabular impingement syndrome (FAIS) using 1-dimensional models created with computed tomography (CT).

Methods

CT scans of bilateral hips in 33 patients diagnosed with unilateral pincer-type or mixed FAIS were obtained. Three-dimensional bilateral hip models were constructed, and the unaffected hemipelvis was superimposed onto the symptomatic side to compare acetabular thickness. Protrusion of the symptomatic side was recorded, and rim morphology was divided into clock face quadrants to analyze the location of greatest magnitude of difference between affected and unaffected acetabula. Analysis of the quadrants was performed using analysis of variance with post hoc Bonferroni correction.

Results

The study group consisted of more females (51.6%) than males, with an average age of 35.72 ± 7.8 years and an average body mass index of 24.3 ± 4.1 kg/m². Of the 33 hips included, 14 were isolated pincer-type FAIS and 19 were mixed. The average preoperative symptomatic side lateral center edge angle was 37.5° ± 7.2° compared with 29° ± 5.1° on the asymptomatic side (P = .001). The symptomatic acetabular rim was on average 0.43 ± 0.18 mm thicker than the corresponding location on the unaffected rim. When the acetabulum was divided into clock face quadrants, the 12 to 3 o'clock position showed the greatest difference between symptomatic and unaffected sides (0.55 ± 0.18 mm) compared with the 3 to 6 o'clock position (0.4 ± 0.28 mm; P = .006), 6 to 9 o'clock (0.34 ± 0.07 mm; P < .001), and 9 to 12 o'clock (0.38 ± 0.03; P = .001).

Conclusions

Patients with unilateral, symptomatic pincer-type or mixed FAIS show statistical differences in rim thickness between the affected and unaffected acetabula. Small changes in acetabular rim morphology on the order of ≤0.5 mm may be the difference between symptomatic FAIS and the unaffected hip.

Level of Evidence

IV, case series.

Limitations of arthroscopy for managing coxa profunda

Coxa profunda is a complex entity that can result in femoro-acetabular impingement (FAI). A meticulous evaluation of the type of acetabular overcoverage is essential to determine which treatment is best suited to each individual patient. Focal overcoverage with no posterior impingement can be treated by arthroscopic recontouring of the disproportionate acetabular wall. Any femoral deformities should be managed during the same procedure. General overcoverage, with predominant postero-inferior impingement, requires open surgery to obtain access to the entire acetabular rim. Rim resection should be sparing, to avoid removing an excessive proportion of the joint surface, yet sufficient to eliminate the impingement. In the event of protrusio acetabuli, which is the extreme form of coxa profunda, reverse peri-acetabular osteotomy should be considered, particularly if the acetabular roof angle is reversed. In some patients, chiefly those with coxa vara, valgus femoral osteotomy should be considered as a means of redirecting the loads towards the acetabular roof, thereby diminishing the forces that tend to drive the femoral head deeper into the socket.

Hip Arthroscopy: Common Problems and Solutions

The use of hip arthroscopy continues to expand. Understanding potential pitfalls and complications associated with hip arthroscopy is paramount to optimizing clinical outcomes and minimizing unfavorable results. Potential pitfalls and complications are associated with preoperative factors such as patient selection, intraoperative factors such as iatrogenic damage, traction-related complications, inadequate correction of deformity, and nerve injury, or postoperative factors such as poor rehabilitation. This article outlines common factors that contribute to less-than-favorable outcomes.

Simultaneous Bilateral Hip Arthroscopy

Many patients are afflicted with painful conditions affecting both hips, most commonly femoroacetabular impingement. Some patients prefer the advantage of undergoing a single surgical procedure and anesthetic followed by a single postoperative rehabilitation program. We present a Technical Note on single-stage bilateral hip arthroscopy. This Technical Note reports on key steps enabling safe and efficient performance of bilateral arthroscopic acetabuloplasty, labral refixation, femoroplasty, and dynamic testing while limiting traction times and facilitating rapid transition to the second hip arthroscopic surgery. Enabling factors include supine positioning with bilateral mobile leg spars, rapid surgical and hip traction times, and postoperative rehabilitation with immediate weight bearing as tolerated. A rationale for deciding which hip should undergo arthroscopy first is also offered. Concurrent bilateral hip arthroscopy is a viable option for select patients and experienced surgical teams, enabling potentially expedited recovery and return to work or sport with inherent cost savings.

Complications in Hip Arthroscopy

BACKGROUND

Recent developments in hip arthroscopic techniques and technology have made it possible in many cases to avoid open surgical dislocation for treating a variety of pathology in the hip. Although early reports suggest favourable results' using hip arthroscopy and it has been shown to be a relatively safe procedure, complications do exist and can sometimes lead to significant morbidity.

METHODS

This is a review article. The aim of this manuscript is to present the most frequent and/or serious complications that could occur at or following hip arthroscopy and some guidelines to avoid these complications.

CONCLUSION

Most complications of hip arthroscopy are minor or transient but serious complications can occur as well. A lot of complication e.g. acetabular labral puncture go unreported. Appropriate education and training, precise and meticulous surgical technique with correct instrumentation, the right indication in the right patient and adherence to advice from mentors and experienced colleagues are all essential factors for a successful outcome. Level of evidence: V.

Dynamic Hip Examination for Assessment of Impingement During Hip Arthroscopy

Arthroscopic procedures for treatment of hip pathology are growing exponentially as a result of continued improvements in the understanding of intra- and extra-articular hip anatomy and technological advancements in instrumentation. Nevertheless, it has been reported that the main cause of revision hip arthroscopy is related to a suboptimal intrasurgical management of the abnormal morphology in femoroacetabular impingement (FAI). Under-resection, over-resection, and in some cases combined under-resection and over-resection at different locations of the cam lesion at the femoral head-neck junction may lead to poor outcomes as a result of residual impingement or the iatrogenic creation of structural instability. Thus, an intraoperative assessment technique capable of revealing in real time the effect of the resection is vital for a successful procedure. Therefore, we present a technical note describing our preferred method to dynamically assess overall hip range of motion, motion at risk, and evaluation of the osteoplasty after surgical correction of FAI.

Imaging in Hip Arthroscopy for Femoroacetabular Impingement: A Comprehensive Approach

Hip arthroscopy has experienced unprecedented growth in recent years and remains an area of booming technology and interest in orthopedic surgery. As understanding of the pathologic state of femoroacetabular impingement (FAI) has grown, imaging modalities have increased. Careful consideration of all bony and soft tissue structures in concert with physical examination findings in nonarthritic patients is necessary before any surgical intervention. This article summarizes the authors' approach to imaging in patients suspected of FAI, which facilitates careful patient selection and preoperative planning.

Effects of acetabular rim trimming on hip joint contact pressures: how much is too much?

BACKGROUND

In patients with femoroacetabular impingement (FAI), acetabular rim trimming removes the offending area of the acetabular deformity in patients with pincer-type and mixed-type FAI to improve hip joint kinematics. Although the rationale for arthroscopic acetabular rim trimming in patients with FAI is well established, the amount of rim resection has not been quantified, and the threshold at which excessive rim resection results in abnormal hip contact pressures has not been described.

PURPOSE

To investigate the changes in contact areas, contact pressures, and peak forces within the hip joint with sequential acetabular rim trimming.

STUDY DESIGN

Controlled laboratory study.

METHODS

Six fresh-frozen, nondysplastic, human cadaveric hemipelvises were analyzed utilizing thin-film piezoresistive load sensors to measure the contact area, contact pressure, and peak force after anterosuperior acetabular rim trimming at depths of 0 mm (intact), 2 mm, 4 mm, 6 mm, and 8 mm. Each specimen was examined at 20° of extension and 60° of flexion. Analysis was performed on 2 regions of interest: the acetabular rim and the acetabular base (deep part of the acetabulum). After each experimental condition, the acetabulum was normalized with respect to the intact state to account for specimen variability. Statistical analysis was conducted through 1-way analysis of variance with post hoc Games-Howell tests.

RESULTS

At the acetabular base, there were significant increases in the contact area after 4-mm resection (60°: 169.12% ± 30.64%; P = .0138), contact pressure after 6-mm resection (60°: 292.76% ± 79.07%; P = .009), and peak force after 6-mm resection (60°: 166.00% ± 34.40%; P = .027). At the acetabular rim, there were significant decreases in the contact area after 6-mm resection (60°: 66.32% ± 18.80%; P = .0354) (20°: 65.47% ± 15.87%; P = .0127), contact pressure after 6-mm resection (60°: 50.77% ± 11.49%; P < .001) (20°: 58.01% ± 23.10%; P = .0335), and peak force after 6-mm resection (60°: 60.67% ± 9.29%; P < .001) (20°: 74.44% ± 9.84%; P = .007).

CONCLUSION

Resecting more than 4 to 6 mm of the acetabular rim during hip arthroscopic surgery to address a pincer deformity may dramatically increase contact pressures by 3-fold at the acetabular base. The study suggests that excessive rim resection may lead to increased loads in the hip joint and may predispose to premature joint degeneration.

CLINICAL RELEVANCE

Resecting more than 4 to 6 mm of the acetabular rim may significantly alter hip joint biomechanics, increasing joint reactive forces and subsequent chondrolabral degeneration.

The effect of acetabular rim recession on anterior acetabular coverage: a cadaveric study using the false-profile radiograph

BACKGROUND

The majority of rim recession for femoroacetabular impingement (FAI) is performed anteriorly and has traditionally been assessed by the lateral center-edge (CE) angle, which correlates most closely with lateral coverage. The radiographic false-profile view permits measurement of anterior coverage via the anterior CE angle and more closely correlates with anterior coverage.

PURPOSE

To answer the following questions: (1) How does incremental anterior rim recession change lateral and anterior CE angles? and (2) Can these changes be predicted by a formula?

STUDY DESIGN

Descriptive laboratory study.

METHODS

Twelve cadaveric hips were dissected free of soft tissue to expose the anterior acetabular rim. Incremental resections of 2.5 mm (range, 0-10 mm) were performed from the 12- to 3-o'clock position using a Dremel rotary tool. Anteroposterior hip and false-profile radiographs were obtained at each interval using a fluoroscopic C-arm. The lateral and anterior CE angles were measured by 3 orthopaedic surgeons.

RESULTS

The average preresection lateral CE angle was 35.1°, and the mean decrease in lateral CE angle from 0 to 10 mm was 9.9°; the average preresection anterior CE angle was 38.4° and the mean decrease in anterior CE angle from 0 to 10 mm was 18.2°. The anterior CE angle decreased by a factor of 1.9 when compared with the lateral CE angle (P = 2 × 10(-7)). The lateral CE angle decreased by approximately 1° (1.0°) per millimeter of rim recessed. The anterior CE angle decreased by approximately 2° (1.8°) per millimeter of rim recessed.

CONCLUSION

The lateral CE angle should not be extrapolated to reflect anterior acetabular coverage. The anterior CE angle is a superior marker and predictably decreases with rim recession at double the rate of the lateral CE angle.

CLINICAL RELEVANCE

The false-profile view is recommended in the perioperative workup for all patients undergoing arthroscopic treatment of pincer impingement.

Arthroscopic surgery for global versus focal pincer femoroacetabular impingement: are the outcomes different?

To determine outcomes from arthroscopic surgery for global pincer femoroacetabular impingement (FAI), a large multicenter prospective study investigating arthroscopic surgical outcomes was performed with minimum 2-year follow-up. Global (center-edge angle 40+ degrees) and Focal (center-edge angle 25-39 degrees) cohorts were based on pre-operative radiographs. Pre-operative and intra-operative findings, surgical procedures, post-operative nonarthritic hip score (NAHS) and satisfaction (5-point Likert scale), complications and conversion arthroplasties were compared. A nested case-control study was also performed. The Global cohort consisted of 15 patients (18 hips) of mean age 37.2 years. Pre-operative NAHS was 51.5 and 74.1 at 24+ months post-surgery. The change in NAHS was significant (P = 0.01). Mean satisfaction was 4.2. There was one total hip arthroplasty (THA) conversion (5.6%), no revision surgeries or complications. The Focal cohort consisted of 125 patients (129 hips) of mean age 39.8 years. Pre-operative NAHS was 54.8 and 77.8 at 24+ months post-surgery. The change in NAHS was significant (P < 0.0001). Mean satisfaction was 4.2. There were eight THA conversions (6.2%), three complications (2.3%) and two revision surgeries (1.5%). Cohort comparisons revealed no statistically significant difference in NAHS (P = 0.30), satisfaction (P = 0.92) or THA conversion rate (P = 0.91). The nested case-control study found mean post-operative change in NAHS was +22.2 and +20.4, respectively, at 24+ months (P = 0.76). Arthroscopic treatment of global pincer FAI is a safe and effective procedure. With outcomes comparable to those observed in the arthroscopic treatment of lesser focal deformities, arthroscopic surgery provides a less invasive option for the treatment of global pincer FAI.

Anchor-induced chondral damage in the hip

The purpose of this study is to investigate the outcomes from anchor-induced chondral damage of the hip, both with and without frank chondral penetration. A multicenter retrospective case series was performed of patients with chondral deformation or penetration during initial hip arthroscopic surgery. Intra-operative findings, post-surgical clinical courses, hip outcome scores and descriptions of arthroscopic treatment in cases requiring revision surgery and anchor removal are reported. Five patients (three females) of mean age 32 years (range, 16-41 years) had documented anchor-induced chondral damage with mean 3.5 years (range, 1.5-6.0 years) follow-up. The 1 o'clock position (four cases) and anterior and mid-anterior portals (two cases each) were most commonly implicated. Two cases of anchor-induced acetabular chondral deformation without frank penetration had successful clinical and radiographic outcomes, while one case progressed from deformation to chondral penetration with clinical worsening. Of the cases that underwent revision hip arthroscopy, all three had confirmed exposed hard anchors which were removed. Two patients have had clinical improvement and one patient underwent early total hip arthroplasty. Anchor-induced chondral deformation without frank chondral penetration may be treated with close clinical and radiographic monitoring with a low threshold for revision surgery and anchor removal. Chondral penetration should be treated with immediate removal of offending hard anchor implants. Preventative measures include distal-based portals, small diameter and short anchors, removable hard anchors, soft suture-based anchors, curved drill and anchor insertion instrumentation and attention to safe trajectories while visualizing the acetabular articular surface.

The modified mid-anterior portal for hip arthroscopy

The modified mid-anterior portal is a utilitarian hip arthroscopy working portal that permits dual-portal comprehensive surgery for femoroacetabular impingement and related chondrolabral procedures without the need for interportal exchange. Its distal location facilitates labral reparative and reconstructive procedures while minimizing iatrogenic acetabular chondral damage. The relatively lateral location permits instrument navigation not only along the anterosuperior acetabular rim and anterolateral proximal femur typically required for acetabuloplasty and femoroplasty but even to the posterior regions of the hip in cases of global pincer femoroacetabular impingement and posterior extensions of cam morphology and the anteromedial proximal femur while avoiding direct injury to the lateral femoral cutaneous nerve.

The critical corner of cam femoroacetabular impingement: clinical support of an emerging concept

PURPOSE

The purpose of this study was to evaluate the concept of cam femoroacetabular impingement (FAI) occurring medial to the classic anterolateral (AL) quadrant.

METHODS

Forty-four patients met the inclusion criteria of cam FAI and underwent arthroscopic AL femoroplasty. Goniometric measurements of intraoperative hip internal rotation (HIR) in 90° of hip flexion and 0° of adduction were obtained. Thirty patients (14 male and 16 female), comprising the substance of this study, exhibited HIR of less than 40° after AL femoroplasty and underwent further anteromedial (AM) femoroplasty with subsequent repeat measurement of HIR. Nonparametric statistical analysis was performed.

RESULTS

Preoperative HIR averaged 20.8° (range, 10° to 29°); intraoperative HIR averaged 29.5° (range, 18° to 39°) after AL femoroplasty and 42.7° (range, 32° to 61°) after additional AM femoroplasty. The gain in HIR after AL femoroplasty was 8.7° (range, 2° to 23°) (P < .0001). The further gain in HIR after AM femoroplasty was 13.2° (range, 2° to 22°) (P < .0001). The overall gain in HIR after AL and AM femoroplasty was 21.9° (range, 13° to 38°) (P < .0001). A consistent landmark termed the resident's ridge of the hip accompanied all cases of AM cam impingement.

CONCLUSIONS

Femoroplasty of the AM "critical corner" may improve cam decompression and supports the concept of cam impingement extending beyond the classic AL quadrant of the proximal femur.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

A comprehensive five-phase rehabilitation programme after hip arthroscopy for femoroacetabular impingement

PURPOSE

Recent advancements in the understanding of hip biomechanics have led to the development of techniques to remove bony impingement and repair and/or preserve the labrum during hip arthroscopy. Although much attention in the literature is devoted to diagnosis and treatment, there is little information about post-operative rehabilitation. Therefore, the purpose of this review is to (1) provide a five-phase rehabilitation protocol following arthroscopic treatment for FAI and (2) report clinical and functional outcomes of patients following this protocol at minimum 1-year follow-up, in order to provide the surgeon and therapist with a protocol that is supported by clinical data.

METHODS

All consecutive patients undergoing hip arthroscopy and subsequent five-phase rehabilitation protocol at a single institution from 1 April 2011 to 1 April 2012 were analysed. Inclusion criteria were as follows: no prior ipsilateral hip surgery, completion of the five-phase rehabilitation protocol, minimum 1-year follow-up, and documented outcome scores. Prospective outcomes were assessed with modified Harris hip score (MHHS) and hip outcome score (HOS).

RESULTS

Fifty-two patients (19 male and 33 female) met the inclusion criteria with a median age of 42 (range 16-59) years. Mean MHHS, HOS-ADL, and HOS-sport scores at a mean 12.5 (range 12-15) months were 80.1 ± 19.9 (0-100), 83.6 ± 19.2 (13.2-100), and 70.3 ± 27.0 (0-100), respectively.

CONCLUSION

This five-phase rehabilitation programme provides a framework where progression from surgery to increasing post-operative activity level can take place in a predictable manner. Patients following this rehabilitation protocol after hip arthroscopy demonstrated satisfactory clinical and functional outcomes, validating its implementation.

Hip arthroscopy for challenging deformities: global pincer femoroacetabular impingement

Pincer femoroacetabular impingement occurs in focal or global forms, the latter having more generalized and typically more extreme acetabular overcoverage. Severe global deformities are often treated with open surgical dislocation of the hip. Arthroscopic technical challenges relate to difficulties with hip distraction; central-compartment access; and instrument navigation, acetabuloplasty, and chondrolabral surgery of the posterior acetabulum. Techniques addressing these challenges are introduced permitting dual-portal hip arthroscopy with central-compartment access, subtotal acetabuloplasty, and circumferential chondrolabral surgery. The modified midanterior portal in combination with a zone-specific sequence of acetabular rim reduction monitored with fluoroscopic templating enables precision subtotal acetabuloplasty. Guidelines for acetabular rim reduction include the following suggested radiographic endpoints: postoperative center-edge angle of 35°, a neutral posterior wall sign, and an anterior margin ratio of 0.5. Arthroscopic zone-specific chondrophobic rim preparation and circumferential labral reparative and reconstructive techniques and tools permit the arthroscopic treatment of these challenging deformities.

Arthroscopic labralization of the hip: an alternative to labral reconstruction

Labralization, which may be performed by open or arthroscopic means, may be an attractive alternative to hip labral reconstruction. By preserving the articular cartilage in the region of labral deficit with meticulous rim trimming, the resultant undermined free chondral margin ("pseudolabrum") may immediately restore a fluid seal function and may theoretically enhance hip preservation. Arthroscopic hip labralization is a relatively simple and fast procedure without graft harvest morbidity. It may be performed in patients tolerating rim reduction with encouraging preliminary outcomes.

Effect of anterior acetabular rim recession on radiographic parameters: an in vivo study

PURPOSE

The purpose of this study was to validate additional radiographic parameters that detect changes within the acetabular cavity during acetabular rim trimming for pincer-type femoroacetabular impingement in an in vivo setting.

METHODS

Patients who met the inclusion criteria and underwent arthroscopic acetabular rim trimming had their preoperative and postoperative anteroposterior radiographs measured. Intraoperatively, these patients had their labrums detached, acetabular walls trimmed by roughly 3 to 5 mm, and then labrums reattached. Radiographic measurements were subsequently obtained by use of the anterior rim angle (ARA), anterior wall angle (AWA), and anterior margin ratio (AMR).

RESULTS

Statistically significant changes were seen in the postoperative ARA, AWA, and AMR. Mean pre- and post-trimming changes were 83.8° and 87.9°, respectively, for the ARA; 38.8° and 35.8°, respectively, for the AWA; and 0.57 and 0.53, respectively, for the AMR. There were no postoperative complications. No patients had any instability events.

CONCLUSIONS

This study shows that significant changes in anterior acetabular anatomy can be evaluated radiographically in the in vivo setting for treatment of pincer-type femoroacetabular impingement. We saw a significant, consistent decrease in both the AWA and AMR and increase in the ARA. This research serves to guide surgeons with preoperative and intraoperative templating while providing the groundwork to investigate these radiographic parameters in an asymptomatic patient population.

CLINICAL RELEVANCE

These novel radiographic measurements can be used by hip arthroscopists to better characterize their surgical role in altering acetabular morphology. In addition, these measurements will be able to better describe acetabular anatomy.

Hip arthroscopy for challenging deformities: posterior cam decompression

Since the classic description of cam femoroacetabular impingement occurring in the anterolateral quadrant of the proximal femur, there has been growing evidence of cam impingement extending outside of this region. Although anteromedial cam decompression may be performed, posterior cam decompression is at higher theoretic risk of vascular embarrassment with osteonecrosis and/or tensile failure with fracture, leading some investigators to believe that these major deformities require open surgical correction. We present a less invasive method of arthroscopic posterior cam decompression using the modified midanterior portal while avoiding the posterolateral vasculature of the proximal femur.

Complications of arthroscopic surgery of the hip

Over recent years hip arthroscopic surgery has evolved into one of the most rapidly expanding fields in orthopaedic surgery. Complications are largely transient and incidences between 0.5% and 6.4% have been reported. However, major complications can and do occur. This article analyses the reported complications and makes recommendations based on the literature review and personal experience on how to minimise them.

Protrusio acetabuli: contraindication or indication for hip arthroscopy? And the case for arthroscopic treatment of global pincer impingement

Protrusio acetabuli has been considered a contraindication for hip arthroscopy. We present the case of a 33-year-old man with bilateral symptomatic protrusio acetabuli-the most extreme form of global pincer femoroacetabular impingement-and cam femoroacetabular impingement. We demonstrate the feasibility of the arthroscopic correction of severe deformities and describe key surgical steps permitting central compartment access, subtotal acetabuloplasty, labral reconstruction, and femoroplasty of the right hip, followed by later subtotal acetabuloplasty, labral refixation, and femoroplasty of the left hip, with improved outcomes at 2 and 1 years, respectively, as measured by the nonarthritic hip score. Though challenging, global pincer impingement, even acetabular protrusion, may be successfully treated with dual-portal outpatient hip arthroscopy. The modified midanterior portal enables central compartment access and extended posterior "reach" in the arthroscopic treatment of major global pincer femoroacetabular impingement, potentially making this contraindication a historical one while respectfully challenging the "global" recommendation for open surgery in this setting.

Adolescent femoroacetabular impingement from malunion of the anteroinferior iliac spine apophysis treated with arthroscopic spinoplasty

This article describes a case of an acute anterior inferior iliac spine apophyseal avulsion fracture in an adolescent athlete progressing to secondary symptomatic femoroacetabular impingement from an inferiorly displaced malunion and its arthroscopic management. A 13-year-old boy with an acute minimally displaced avulsion fracture of the anterior inferior iliac spine apophysis had initial symptomatic improvement with conservative treatment and a 3-month symptom-free period but then developed flexion-induced deep anterior groin pain and mechanical symptoms. Radiographs confirmed an inferiorly displaced malunion of the ipsilateral anterior inferior iliac spine apophysis in addition to acetabular retroversion and cam deformity. Surgical treatment, including arthroscopic spinoplasty, was performed. Despite some nonrestrictive heterotopic ossification, the patient had a successful clinical outcome at 18 months, with return to football, and a nonarthritic hip score of 98. Although anterior inferior iliac spine avulsion fractures have historically been considered relatively self-limiting injuries, their malunion may be a previously missed cause of unrelenting or bimodal pain from secondary femoroacetabular impingement with possible degenerative consequences in young athletic patients. Anterior inferior iliac spine avulsion fractures may merit a lower degree of tolerance for displacement in the acute setting and a higher degree of clinical and radiographic scrutiny with surgical intervention, possibly in the form of arthroscopic spinoplasty in the more chronic one.

Arthroscopic labral reconstruction with gracilis autograft

Despite growing interest in hip arthroscopy and labral preservation, some patients have severely damaged, degenerative, or deficient labrums and may be candidates for arthroscopic labral reconstruction. The ligamentum teres has been used as a graft source for open hip labral grafting, and the iliotibial band has been used in the arthroscopic setting. We present an alternative method of hip labral reconstruction using the gracilis autograft, which does not require post-harvest manipulation. Arthroscopic techniques for graft tensioning and labrum-graft overlap are introduced that may facilitate restoration of labral function in patients with otherwise non-salvageable labrums.

The clamshell fracture and adjunctive acetabuloplasty in the arthroscopic osteosynthesis of femoral head fractures with femoroacetabular impingement

The clamshell fracture of the femoral head and its arthroscopic osteosynthesis are described. This suprafoveal osteochondral fracture may have folded onto itself during closed reduction of the associated anterior hip dislocation. The resultant fracture fragment had almost circumferential chondral coverage that required arthroscopic manipulation to "pry apart the clamshell," permitting arthroscopic reduction. This patient also had pre-existing silent femoroacetabular impingement, and the novel use of arthroscopic acetabuloplasty permitted internal fixation by improving the path for headless screw fixation. The arthroscopic techniques and clinical outcome at greater than 2 years are presented. Albeit rare, the clamshell fracture configuration should be recognized and may be amenable to successful arthroscopic osteosynthesis. Of broader clinical impact and application, adjunctive acetabuloplasty may permit the successful osteosynthesis of select femoral head fractures in patients with concurrent acetabular overcoverage by completely arthroscopic techniques that engage both the fracture fragment and the attractive benefits of less invasive surgery.

Computer-assisted modeling of osseous impingement and resection in femoroacetabular impingement

PURPOSE

The purpose of this study was to evaluate the utility of computer-assisted 3-dimensional modeling in diagnosing and treating symptomatic hip impingement.

METHODS

Eight patients with symptomatic, focal cam and/or pincer impingement lesions underwent high-resolution computed tomography scans and computer-assisted, 3-dimensional modeling of the involved hip. Cam location, alpha angle, neck-shaft angle, femoral version, and acetabular version at the 12-o'clock through 3-o'clock positions were measured. The model was subsequently dynamized to define the preoperative range of motion and location of impingement with hip flexion, internal rotation, and internal rotation at 90° of hip flexion. Virtual cam and pincer osteoplasty was performed to establish normal head-neck offset and head sphericity and to eliminate focal rim impingement lesions. Range of motion and location of impingement were reassessed after resection in the defined area of impingement.

RESULTS

The cam lesion was located between the 12-o'clock and 4-o'clock positions in all cases. The mean alpha angle was 66.4° (range, 53° to 80°). Mean femoral version was 14.6° (range, 5° to 23°). Mean preoperative hip flexion was 109.7° (range, 87.5° to 125.5°), and mean internal rotation at 90° of hip flexion was 16.2° (range, 1.7° to 25.5°). The location of impingement was unique in each case and not predictable based on radiographic measures alone. Virtual osteoplasty in the defined regions of impingement resulted in significant improvements in both hip flexion and internal rotation (P < .05).

CONCLUSIONS

Computed tomography-based computer modeling can localize regions of anticipated mechanical impingement in symptomatic patients with hip pain. Computer-assisted navigation may be a valuable surgical tool to more accurately and reliably eliminate offending impingement lesions.

LEVEL OF EVIDENCE

Level IV, diagnostic study.

Surgical treatment of femoroacetabular impingement improves hip kinematics: a computer-assisted model

BACKGROUND

Femoroacetabular impingement (FAI) is now recognized as the most common cause of early osteoarthritis in the nondysplastic hip. While the surgical treatment of FAI has demonstrated favorable clinical outcomes, the ability of an osteoplasty to reliably improve hip kinematics and range of motion remains unknown.

PURPOSE

This study used computer-assisted 3-dimensional (3D) analysis to assess differences in hip range of motion before and after the arthroscopic surgical treatment of symptomatic FAI.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Ten patients with symptomatic, focal cam and/or pincer impingement lesions underwent high-resolution computed tomography scans and computer-assisted 3D modeling of the involved hip before and after corrective arthroscopic surgery by the senior author. Cam location, alpha angle, neck-shaft angle, femoral version, and acetabular version at 12-o'clock through 3-o'clock positions were measured. The model was subsequently dynamized to define the preoperative and postoperative range of motion and location of impingement with hip flexion, internal rotation, and internal rotation at 90° of hip flexion. Statistical analysis of preoperative and postoperative hip flexion and internal rotation at 90° of hip flexion was performed using paired t tests with P < .05 defined as significant.

RESULTS

The cam lesion was located between 12 o'clock and 5 o'clock in all cases. Mean preoperative alpha angle was 59.8° (range, 36°-76°). Mean femoral version was 12.5° (range, -15° to 32°). Mean preoperative hip flexion was 107.40° ± 11.6°, and mean internal rotation at 90° of hip flexion was 19.10° ± 13.0°. The location of impingement was unique in each case and not predictable based on simple radiographic measures (ie, alpha angle) alone. Corrective femoral and rim osteoplasty resulted in significant improvements in both hip flexion (3.8°; P = .002) and internal rotation (9.3°; P = .0002). Mean postoperative alpha angle was 36.4° (range, 22°-46°).

CONCLUSION

Focal cam and/or rim osteoplasty can reliably improve hip kinematics and range of motion in patients with symptomatic FAI, particularly the limitation of internal rotation in a flexed position. Computed tomography-based computer modeling can localize regions of anticipated mechanical impingement in symptomatic patients. A complete osteoplasty in these defined regions, through an arthroscopic or open approach, predictably improves range of motion and may help to eliminate the recurrent mechanical collision and secondary chondral injury associated with FAI.

Fluoroscopic demonstration of femoroacetabular impingement during hip arthroscopy

Femoroacetabular impingement is a cause of hip pain that in selected cases can be treated by removal of impinging bone (osteoplasty). No absolute parameters for osteoplasty exist. We present a technique for dynamic evaluation of bony impingement and control of arthroscopic osteoplasty using intraoperative fluoroscopy. With the patient supine on a fracture table, the C-arm is positioned between the legs. Femoral anteversion is measured with the C-arm vertical and the hip flexed 90° (Dunn view). The C-arm is then tilted back 25° from vertical to create a profile view of the anterior rim, and the hip is flexed under fluoroscopy to find the location of maximum head/neck deformity. Because the distance between rim and neck is apparent, a spot view in that position is used to plan the osteoplasties. Impingement is demonstrated by forced internal rotation and is obvious as bony contact, movement of the pelvis, or joint subluxation. Osteoplasty of the neck is performed with the hip extended and the C-arm tilted to reproduce the view of the maximum neck deformity. The dynamic examination is repeated to confirm adequacy of the osteoplasty and improvement in internal rotation. Hip deformities could be efficiently identified and individually corrected.

Use of intraoperative computed tomography scanning in determining the magnitude of arthroscopic osteochondroplasty

Femoroacetabular impingement has recently become a recognized cause of disability and hip arthritis. Hip arthroscopy and femoroacetabular reshaping have been performed to treat this condition. Quantification of the excess femoral and acetabular bone requiring resection has been challenging with the less invasive arthroscopic technique. We describe the use of intraoperative computed tomography assessing osteochondroplasty during arthroscopic surgery to treat cam- and pincer-type femoroacetabular impingement. We also describe the technical steps and present the important radiologic findings we have been able to visualize. We found intraoperative computed tomography scanning to be a reliable and reproducible method of assessing the quality of femoroacetabular impingement surgery. We believe that femoroacetabular impingement surgery can be assessed intraoperatively by use of computed tomography scanning where corrections can be made if necessary.

The case for cam surveillance: the arthroscopic detection of cam femoroacetabular impingement missed on preoperative imaging and its significance

Classification of femoroacetabular impingement is typically determined by preoperative imaging. Despite measurements such as the alpha angle and anterior offset ratio, cam dysmorphisms may be missed. We present 2 cases of femoroacetabular impingement classified as pincer subtypes where significant cam lesions were not detected until surgery. Arthroscopic cam surveillance includes the intentional visualization of the anterior and lateral proximal head-neck junctional region from the peripheral compartment performed with capsular retraction and/or partial capsulectomy. Static and dynamic cam surveillance of the proximal femur is recommended before the termination of surgery for hip chondrolabral dysfunction and has even greater significance in the arthroscopic management of these patients.

Can the change in center-edge angle during pincer trimming be reliably predicted?

BACKGROUND

Femoroacetabular impingement is recognized as a cause of hip pain in young adults and as a precursor to osteoarthritis although many questions persist regarding its management. One in particular is when to resect a pincer lesion and how much to resect. Instability can result from overresection and persistent impingement can result from underresection.

QUESTIONS/PURPOSES

We therefore determined the correlation between the change in center-edge (CE) angle and the amount of acetabular rim resection.

METHODS

We performed open acetabular rim trimming on 10 cadaveric hips. Radiographs were performed before and after rim resection every millimeter from 1 to 5 mm and we determined the CE angle. We performed linear regression to establish any correlation of the CE angle with the amount of resection.

RESULTS

The CE angle could be predicted by -1.3X + 1.5 (R(2) = 0.99), in which X = the amount of resection for 1 to 3 mm of resection. The average CE angle before resection was 35° ± 8.8° (range, 19°-58°).

CONCLUSIONS

The CE angle changes in a predictable way with acetabular rim trimming with larger amounts of resection resulting in greater changes in the CE angle.

CLINICAL RELEVANCE

The ability to accurately plan the amount of acetabular rim resection in hip arthroscopy by knowing the exact change in CE angle with amount of rim removal may help prevent overresection or underresection in pincer trimming.

Static and dynamic mechanical causes of hip pain

Mechanical hip pain typically has been associated either with dynamic factors resulting in abnormal stress and contact between the femoral head and acetabular rim when the hip is in motion or with static overload stresses related to insufficient congruency between the head and acetabular socket in the axially loaded (standing) position. Compensatory motion may adversely affect the dynamic muscle forces in the pelvic region, leading to further strain and pain. Hip pain related to static overload stresses may also be localized to the anteromedial groin, but compensatory dysfunction of the periarticular musculature may lead to muscular fatigue and associated pain throughout the hip. As our understanding of hip joint mechanics has advanced, it has become increasingly apparent that hip pain in the absence of osteoarthritis may be due to a complex combination of mechanical stresses, both dynamic and static. With an emphasis on findings in the recent literature, this review will describe the dynamic and static factors associated with mechanical hip pain, the combinations of dynamic and static stresses that are commonly identified in hip pain, and common patterns of compensatory injury in patients with femoroacetabular impingement.

Assessment of arthroscopic management of femoroacetabular impingement. A prospective multicenter study

INTRODUCTION

Surgical treatment of femoroacetabular impingement can be performed under arthroscopic control, to limit associated morbidity. Encouraged by recent good reports, arthroscopy is replacing alternative techniques for this indication.

HYPOTHESIS

Arthroscopy enables femoroacetabular impingement to be corrected with a low rate of associated morbidity.

AIM OF STUDY

To assess the indications for and quality of the technique and its impact on preliminary results and complications. To investigate preoperative prognostic factors.

PATIENT AND METHODS

One hundred and eleven hips in 110 patients (78 male, 32 female; mean age, 31 years) were operated on under arthroscopic control for femoroacetabular impingement, by six senior surgeons. Sixty-five patients showed no radiographic sign of osteoarthritis, and 36 showed grade-1 early osteoarthritis on the Tönnis scale.

RESULTS

Mean WOMAC score rose from 60.3 preoperatively to 83 (p<0.001) at a mean 10 months' FU (range, 6-18 mo). Seventy-seven percent of patients were satisfied or very satisfied with their result. Patients with early osteoarthritis had significantly lower WOMAC and satisfaction scores than those free of osteoarthritis. Operative crossover to open surgery occurred in only one case. Five patients (4%) had revision: total hip replacement or resurfacing. There were seven complications (6%): three cases of heterotopic ossification, one of crural palsy, one of pudendal palsy, one of labium majus necrosis, and one non-displacement stress fracture of the femoral head/neck junction (managed by non-weight-bearing). There was no palsy of the territory of the lateral cutaneous nerve of the thigh.

DISCUSSION

Results confirmed the efficacy and low associated morbidity of arthroscopy in the management of femoroacetabular impingement. Short-term functional results matched those of the literature. Planning and assessment seem not yet to be fully standardized. Preoperative osteoarthritis on X-ray was associated with poorer functional results. This attitude does not seem to be indicated for hips showing evolved osteoarthritis (>grade 1).